1. Field of the Invention
This invention relates to the field of fluid pumps in general, and in particular, to a rotary input positive displacement pump having an off-axis drive shaft and accompanying eccentric structural operation.
Rotary driven fluid pumps have been disclosed, for example, in the following U.S. Pat. Nos. 219,365; 1,806,206; 2,316,318; 3,894,819; 3,288,119; 3,551,080; 3,299,822; 3,671,153; 3,387,772; 3,716,314; 4,150,926; and 4,278,409. A rotary driven fluid pump is also disclosed in British Pat. No. 13,070 (of 1884). Typically, the fluid pumps described in the foregoing references have a number of significant shortcomings. The seals between the stationary housing and the rotating member wear out very quickly. Flexible vane pumps are incapable of producing high pressure. Although gear-type pumps are capable of producing high pressure, they tend to be relatively low volume devices.
A first significant improvement over such prior art rotary pumps is disclosed in my U.S. Pat. No. 4,431,391. A high-volume positive displacement pump has a rotationally driven blade which creates a pressure differential, and therefore a fluid flow within a circular pump case cavity split by the blade. As the blade is rotatably driven about an axis which is non-aligned with the center of the circular case, the unique geometry provides high fluid flow characteristics. A unique sealing means was provided between the ends of the rotating blade and the cavity ring portion of the circular case in the form of concentric rings within the case. More particularly, the ends of the rotating blade were sealed relative to the inner circular wall of the stationary casing by a partial inner and outer mating pair of concentric circular rings, matingly seated for rotation within the casing and driven by the inter-connecting ends of the blade. One end of the blade is pivotably locked to the partial ring while the other end of the blade is pivotally and slidably held by an intermediate knuckle in the outer ring. A sliding movement occurs between the knuckle and the mating end of the blade to accommodate the off-center rotational geometry of the rotating blade.
Although the pump disclosed in my earlier patent was most effective, a result of using concentric circular rings is that the volume of the pumping cavity available for pumping is reduced in volume, at least by the volume of the inner partial concentric ring.
In order to develop a rotary force positive displacement pump which could take advantage of the unique geometry of my earlier pump, but which at the same time had the advantage of increased pumping volume capacity, it was necessary to develop new blade sealing and mounting systems. Generally speaking, a rotary force fluid pump according to the new blade sealing and mounting systems comprises: a housing defining a circular cylindrical pumping chamber; a blade means for moving fluid through the pumping chamber; at least one blade means positioning ring mounted for rotation around the periphery of the pumping chamber; eccentrically disposed drive means for slidably engaging and rotating the blade means in the pumping chamber; means enabling the blade means to rotatably drive the blade positioning ring and accommodate the eccentric rotation of the blade; and, fluid intake and exhaust ports. Accordingly, the pumps disclosed herein utilize an arrangement for positioning the blade, an arrangement for a blade assembly and a means for sealing the ends of the blade assembly which are entirely novel with respect to my earlier pump, but at the same time, preserve the unique and effective pumping geometry. In particular, and disposed in a similar housing defining a circular cylindrical pumping chamber, a first embodiment of the new pump includes a stacked pair of blade positioning rings mounted for independent rotation around the periphery of the pumping chamber. Instead of having concentric rings, one disposed inside the other, so as to reduce the volume of the pumping chamber, the rings of this pump are stacked one above the other, taking up no more room in the pumping chamber than the outer ring of the earlier pump.
The blade assembly of the new pump is pivotally mounted at each end to a different one of the rings, yet still divides the pumping chamber into two sections which vary in volume as the blade assembly rotates. Whereas the blade of the earlier pump was fixedly and pivotally mounted at one end, to the inner ring, and pivotally and slideably mounted at the other end to the outer ring, the blade assembly of the new pump is pivotally and fixedly mounted at each end to a different one of the stacked rings. In other words, one end of the blade assembly is pivotally and fixedly mounted to the upper ring, and the other end of the blade assembly is pivotally and fixedly mounted to the lower ring. In both pumps, eccentrically disposed drive means slidably engage and rotate the blade or blade assembly in the pumping chamber. In both instances, the blade in turn rotatably drives the two rings at different speeds relative to one another, causing the points of attachment of the blade or blade assembly to the rings to move toward and away from one another during rotation. The angular orientation of the lengthwise blade axis relative to each of the rings also changes, and changes differently, during rotation. The new pump includes means incorporated into the blade assembly for accommodating the relative movement of the pivotally and fixedly mounted ends of the blade assembly, and in particular, comprises two rigid parts with slidably interfitting structure.
Finally, the new pump utilizes resilient means disposed between the inner surfaces of the positioning rings and corresponding inner surface engaging structure of the blade assembly. The resilient sealing means include an elongated semi-cylindrical seal carried by each end of the blade assembly in a semi-circular notch which slidably receives each seal. The substantially flat surface of each seal slidably engages the inner surfaces of the positioning rings. The seals are free to rotate within the mounting structure of the blade assembly in order to accommodate the different angular orientations between the lengthwise blade axis and a tangent line of the ring at the point of pivotal attachment.
In a second embodiment, the new rotary force fluid pump comprises: a housing defining a circular cylindrical pumping chamber; a blade disposed in the pumping chamber; a blade positioning ring mounted for rotation around the periphery of the pumping chamber; eccentrically disposed drive means for slidably engaging and rotating the blade in the pumping chamber; means effecting sequential engagement and disengagement of the blade to preselected positions on the ring during rotation, which together with the sliding movement between the blade and the drive means, change the effective length of the blade during the eccentric rotation; and, fluid intake and exhaust ports.
Overall, the new pumps provide significant advantages in enhanced pumping capacity.